Cassava-starch plastic composition and method of molding same



-gilsonite may be used Patented Apr. 3, 1928.

UNITED STATES APAJ'IENTIOFFICE.

, cmnron arms, or ammonia, mew inssnx, nssrezton. 'ronLLIs-roernaoollrun, A OOBPOBATION OF NEW JERSEY.

(N Y r OABSAVA-S'I'ABGE PLASTIC GOIPOB ITION AN D IETHOD OI IO LDIHG V10 Drawing. Application filed Kay i7, 1m, Serial lie. 113,171.lenewedlal y 14, 10".

This invention relates to a composition containing cassava starchtogether with certain resins and extending a ents, all as will be morefully hereinafter escribed.

The present invention is directed to the use of cassava starch as abinding a t to secure a stren h in molded artic es not readily obtainale when corn starch, wheat starch potato starch, and the like, areemploye In carrying out my invention I do not reclude the employment'ofsuch other stare es, but essentially the composition must containcassava starch.

With the cassava starch I incorporate a resinous substance such asmanila, congo or pontianac resin, rosin ester, and/or ordinary rosin,especially the ty e known as wood rosin or stum rosin. ther resinoussubstances and a so pitches, asphalts and in some cases. bark coloredmolded articles are obtainedwhen such asphaltic bodies are employed,whereas with some of the resins such as ordinary rosin or stump rosin,light colored molded articles result. The composition may be tinted asuitable color with appropriate pigments or dyes. Agents such asessential oils, e. g., oil of cedarwood, may be added to give tlcileproduct 'a definite or readily recognized 0 or.

An extendin material such as ground wood or wood fiour also preferabl ispres ent. Other powdered material suc as clay, talc, whiting, asbestosfibre, ground asbestos and asbestine, wood flock, cotton linters, andthe like, also may be resent.

Water also prefera ly is present in considerable quantity. In any event,a sufiicient amount is desired to burst the cassava starch granules whenthese are exposed to heat is molding. In some cases, it is preferable tobreak up the cassava starch to some extent by pre-cooking, or othertreatment. The water gives the composition a greater flowing power, sothat it may be molded in shapes of quite large dimensions, but whenmolding ieces of from moderate to large size consi erable care isrequired to permit of the escape of the moisture from the hot mold. Thewater may contain a small amount of glycerol, or in some cases, maycarry an emulsion of parafiin wax or other wax emulsion, e. g.,carnauba, to allow of special waterproofing effects and the like.

A composition which may be made cheaply tars is composed of thefollowing illustrative in- I gradients, the proportions being by'weight:

M Powdered rosin 140 Cassava starch 240 Wood flour 440 Water 400 to 500These ingredients are mixed in a Werner & Pfleiderer mixing machine orother suitable mixing device, and when uniformly mixed the compositionis ready for use.

A quantity is placed in a hot mold and the plunger applied, giving apressure of several pounds, or more, to the square inch. Preferably thesides of the mold are made slightly tapering to allow the escape ofsteam, or the plun er may be withdrawn part way during the first stagesof the pressing, as this procedure ermits of the escape of excessmoisture. tween 150-200 although higher temperatures may be emplo ed insome cases.

An object is to ave the proportion of. water such that it is absorbed bythe wood fiour and when the mixture is subjected to hot pressin themoisture ruptures the cassava stare granules, and the starchy solutionor paste t us produced forming about the rosin and Wood flour creates acondition whereby the composition .tends to harden in the press and t usmakes possible the removal of the molded article while it is still 7fairly hot. This enables the ressing operation to be carried on rapid ywithout the necessity of cooling the mold before removal of the plasticarticle.

The invention therefore comprises molded articles made from cassavastarch, a resin and a finely-divided extendin agent and the process sifically adaptab e to a molding compositlon containing water is that ofcarrying out hot pressing under conditions which allow of the escape ofsteam, whereby further drying out in the mold occurs and hardenin takesplace sufiiciently to enable the with rawal from the mold of a moldedarticle, which, althou' h hot, is not readily deformed by the hand ingwhich necesarily ensues.

As indicated, the composition given above is illustrative and variousmodifications may be made including a considerable variation inproportions.

In a copending case 108,987 filed May 13,

' he temserature is preferably beion and 'referably also Water, withwhich may 5 also Be included various resins and adhesive substances,such composition when hot molded, having the property of thermo-setting.

What I claim is: ,1. A molded article comprising cassava starch, a resinand wood flour.

2. A molded article comprising cassava starch, rosin, and finely-dividedextending material.

3. The process of making molded articles from a mixture of cassavastarch, rosin, wood flour and water, which comprises hotpressing such amixture in a suitable mold and permitting the escape of steam during thepresng stage.

, GARLETON ELLIS.

